The present invention relates, in general, to knee bolsters used in vehicles to protect the knees of vehicle occupants, such as during the event of a collision or crash. More particularly, the invention relates to an improved knee bolster that is easier to manufacture and assemble and/or provides an improved stepped crush (i.e., controlled deflection) when forcibly impacted. In one embodiment, the improved knee bolster employs varied thicknesses and/or dimensions to provide a two-step deflection versus force curve, i.e., a particular stepped crush, when a force is applied to the knee bolster, such as a knee impacting the knee bolster during a collision. The improved knee bolster will be described with particular reference to this and like embodiments, but it is to be appreciated that the knee bolster is also amenable to other like applications.
It is well known to use a knee bolster on or adjacent a vehicle's front dashboard, such as on either side of the vehicle's steering column extending from the front dashboard. Examples of such an arrangement are provided in U.S. Pat. Nos. 5,037,130 to Okuyama and 5,370,417 to Kelman et al., both expressly incorporated herein by reference. Another knee bolster example is disclosed in commonly-owned, U.S. Pat. No. 4,893,834, also expressly incorporated herein by reference.
It is known to attempt to control the crush (i.e., deflection relative to impact force) of a knee bolster. Various types of knew bolsters have been proposed for this purpose. Examples of such knee bolsters are disclosed in U.S. Pat. Nos. 5,273,314 to Sakakibara; 5,549,327 to Rüsche et al.; and 6,609,727 to Figlioli et al., all expressly incorporated herein by reference. The '314 and '727 patents disclose step-shaped knee bolsters, whereas the '327 patent discloses a knee bolster having a wall with a progressively dimensioned thickness, to control the rate of crush.
Prior art knee bolster, however, are often overly complex requiring complicated and/or costly processes for making the components which ultimately form the knee bolster. In addition, prior art knee bolsters often require difficult assembly procedures for assembly and/or installation into a vehicle. Still further, prior art knee bolsters are often difficult to modify for purposes of adjusting responsiveness to impact loads applied thereagainst.